Windows 8 Will Favor IPv6, But Continue IPv4 Support

Windows 8 will support both IPv4 and IPv6 connectivity but will "prefer" the newer standard when both connection modes are available, according to a posting on the "Building Windows 8" blog.

While all releases of Windows since Windows XP SP3 have supported the long-gestating IPv6 Internet protocol standard, the forthcoming Windows 8 will be the first to favor the new Internet standard that's being implemented worldwide to eliminate the shortage of IP addresses.

"Our primary focus during this transition has always been to minimize the impact of the transition for everyday users," wrote Christopher Palmer, a member of the Windows 8 core networking program management team, in the blog. "It shouldn't matter whether your connection is over IPv4 or IPv6. You should have an Internet experience that is fast and reliable, with little evidence of the IPv6 transition, so you can just enjoy the content."

[Related: World IPv6 Launch Day: Security Vulnerability Or Channel Opportunity? ]

"At the same time, it's also a priority for us to help the IPv6 transition move ahead. To this end, Windows prefers native IPv6 connectivity over IPv4 connectivity, if both connection modes are available," Palmer wrote.

Last week Microsoft debuted Windows 8 Release Preview, a version of the product that customers and partners can begin to work with in advance of the final "Release to Manufacturing" version that's expected later this year.

IPv4 has been under development for years, and yesterday was designated "World IPv6 Launch Day" in an effort to get major Internet service providers to switch to the new IP protocol. While some ISPs have already done that, Palmer said many have only just started rolling out IPv6 support. And, only about 1 percent of computing devices can connect to the Internet using only IPv6, Palmer said.

While some ISP networks will only support IPv4 or IPv6 during the transition, many networks will support both through a "dual-stack" approach that configures PCs and mobile devices trying to access the Internet with both IPv4 and IPv6 addresses.

"Windows 8 is designed to ensure connectivity across all types of network configurations," according to Palmer. The new operating system will support dual-stack networks. But, Windows 8 "automatically attempts IPv6 connectivity when the server does not offer an IPv4 address," he said.

NEXT: Windows 8 Address Sorting And Testing

Because Windows 8 will support both IPv4 and IPv6, the operating system will incorporate a functionality called "address sorting" that will figure out the best pair of IP addresses to use when connecting a PC or device to the Internet. Windows, according to Microsoft's Palmer, will sort through its own IP addresses and those of a dual-stack Website and decide what combination will provide the best connection.

Windows 8 also will test IPv6 connectivity when it connects to a new network that advertises IPv6 routability and use the new standard only if it's actually functioning. Windows 8 caches the test information and repeats the test every 30 days. If both IPv4 and IPv6 are supported, Windows 8 will prefer the new standard

Windows 8 will provide these capabilities not only for Microsoft's Internet Explorer browser but also for applications running on Windows -- both existing applications and those built on the Windows 8 Metro interface -- that need to connect to network resources.

Later this month, the Bing search engine and other Microsoft sites will start serving traffic over IPv6. When Windows 8 is released later this year, some Microsoft infrastructure services will deploy IPv6 support. The Windows Update service currently supports both IPv4 and IPv6.